
@article {113539,
	title = {An inducible potato (E,E)-farnesol synthase confers tolerance against bacterial pathogens in potato and tobacco.},
	journal = {Plant J},
	year = {2022},
	month = {2022 Jul 02},
	abstract = {<p>Terpene synthases (TPSs) have diverse biological functions in plants. Though the roles of TPSs in herbivore defense are well established in many plant species, their role in bacterial defense has been scarce and is emerging. Through functional genomics, here we report the in planta role of potato (Solanum tuberosum) terpene synthase (StTPS18) in bacterial defense. Expression of StTPS18 was highest in leaves and was induced in response to Pseudomonas syringae and methyl jasmonate treatments. The recombinant StTPS18 exhibited bona fide (E,E)-farnesol synthase activity forming a sesquiterpenoid, (E,E)-farnesol as the sole product, utilising (E,E)-farnesyl diphosphate (FPP). Subcellular localization of GFP fusion protein revealed that StTPS18 is localized to the cytosol. Silencing and overexpression of StTPS18 in potato resulted in reduced and enhanced tolerance, respectively, to bacterial pathogens P. syringae and Ralstonia solanacearum. Bacterial growth assay using medium containing (E,E)-farnesol significantly inhibited P. syringae growth. Moreover, StTPS18 overexpressing transgenic potato and Nicotiana tabacum leaves, and (E,E)-farnesol and P. syringae infiltrated potato leaves exhibited elevated expression of sterol pathway and members of pathogenesis-related genes with enhanced phytosterol accumulation. Interestingly, enhanced phytosterols in C -(E,E)-farnesol infiltrated potato leaves were devoid of any noticeable C labeling, indicating no direct utilization of (E,E)-farnesol in phytosterols formation. Furthermore, leaves of StTPS18 overexpressing transgenic lines had no detectable (E,E)-farnesol similar to the control plant, and emitted lower levels of sesquiterpenes than the control. These findings point towards an indirect involvement of StTPS18 and its product (E,E)-farnesol in bacterial defense through upregulation of phytosterol biosynthesis and defense genes.</p>
},
	issn = {1365-313X},
	doi = {10.1111/tpj.15890},
	author = {Dwivedi, Varun and Kumar, Sarma Rajeev and Shilpashree, H B and Krishna, Ram and Rao, Srinivas and Shasany, Ajit K and Olsson, Shannon B and Nagegowda, Dinesh A}
}
@article {82441,
	title = {Functional characterization of a defense-responsive bulnesol/elemol synthase from potato.},
	journal = {Physiol Plant},
	volume = {171},
	year = {2021},
	month = {2020 Sep 03},
	pages = {7-21},
	abstract = {<p>Terpene synthases (TPSs) produce a variety of terpenoids that play numerous functional roles in primary and secondary metabolism, as well as in ecological interactions. Here, we report the functional characterization of an inducible potato TPS gene encoding bulnesol/elemol synthase (StBUS/ELS). The expression of StBUS/ELS in potato leaves was significantly induced in response to both bacterial (Pseudomonas syringae) and fungal (Alternaria solani) infection as well as methyl jasmonate treatment, indicating its role in defense. The leaves exhibited the highest StBUS/ELS expression followed by the stem with least and similar expression in tuber, sprout and root. Recombinant StBUS/ELS catalyzed the formation of different sesquiterpenes by utilizing farnesyl diphosphate as substrate, and the monoterpene geraniol from geranyl diphosphate. Among the sesquiterpenes formed by StBUS/ELS, elemol was the predominant product followed by α-bulnesene, bulnesol, and β-elemene. Further GC-MS analysis of StBUS/ELS assay products at different injection temperatures revealed elemol and bulnesol as the major products at 275{\textdegree}C and 200/150{\textdegree}C, respectively, without much change in the levels of minor products. This indicated thermal rearrangement of bulnesol into elemol at higher temperatures. Transient overexpression of StBUS/ELS in potato leaves conferred tolerance against the growth of bacteria P. syringae and Ralstonia solanacearum, and the fungus A. solani. Further, expression analysis of pathogenesis-related (PR) genes in StBUS/ELS overexpressing leaves showed no significant change in comparison to control, indicating a direct involvement of StBUS/ELS enzymatic products against pathogens. Overall, our study suggested that StBUS/ELS is a pathogen-inducible TPS encoding bulnesol/elemol synthase and could provide a direct role in defense against biotic stress in potato.</p>
},
	issn = {1399-3054},
	doi = {10.1111/ppl.13199},
	author = {Dwivedi, Varun and Rao, Srinivas and Bomzan, Dikki Pedenla and Kumar, Sarma Rajeev and Shanmugam, Pragadheesh V and Olsson, Shannon B and Nagegowda, Dinesh A}
}
